The frequency of a laser can be converted, for example, doubled, with a nonlinear element. U.S. Pat. No. 4,618,957 discloses a laser arrangement wherein a nonlinear crystal is mounted in the resonator for doubling frequency. The resonator has a deflected beam path with the mirror at the deflection location operating to couple out the beam having the doubled frequency.
This known arrangement has the disadvantage that it only emits radiation having the doubled frequency. Furthermore, this known arrangement requires a relatively large mounting area because of the deflected beam path.
In addition to a doubling of frequency, other conversions can be carried out with nonlinear elements, such as a tripling of frequency or a Raman conversion.